This invention relates to apparatus using order wires for communication between a local station and a counterpart station by a telephone set and a facsimile set. In other words, order wires are used in this invention rather than public wires.
In general, order wires are of a four-wire type. The apparatus of the type described in this application is used for receiving and transmitting through the order wires four-line input signals and four-line output signals, respectively. At least one of the input signals is a specific signal including a called number signal indicative of supply of the specific signal to the local station. Similarly, at least one of the output signals is a specific signal including a calling number signal indicative of transmission of the specific signal to the counterpart station.
In the prior art, such apparatus comprises a processing circuit connected to the order wires for processing the input signals into an input single signal including the called number signal, and for processing an output single signal into the output signals including the calling number signal. The output single signal is produced by a telephone set in the local station.
An input detecting circuit is connected to the processing circuit and detects the input control signal in the input single signal as a detected signal.
An input judging circuit is connected to the input detecting circuit and judges whether the detected signal indicates supply of the input single signal to the local station or not. The input judging circuit produces an input connection signal indicative of the local station after having judged that the detected signal indicates supply of the input single signal to the local station.
An output producing circuit produces an indicating signal indicative of production of the output single signal by the local station.
An output judging circuit is connected to the output producing circuit and produces an output connection signal indicative of the counterpart station.
A supplying circuit is connected to the output judging circuit and supplies the output single signal with the calling number signal indicative of supply of the output single signal to the counterpart station in response to the output connection signal.
A connecting unit is connected to the input judging circuit and connects the processing circuit to the telephone set in the local station when the input connection signal indicates the local station. The connecting unit is connected to the output judging circuit and connects the processing circuit to the telephone set in the local station in response to the output connection signal.
It has now been found by the present inventor that the aforementioned apparatus of the prior art enables communication between stations by a telephone set through the order wires even if there are no public wires between the stations.
However, when the apparatus is used for communicating between the local and the counterpart stations by a facsimile set, it is necessary to use the public wires. As a result, the apparatus cannot communicate between stations by the facsimile set without the public wires.